Family Bulinidae 197 



The head is very broad and has its lower margin exi)anded and flattened. 

 The tentacles are elongate and filiform. The eyes lie at the inner base of 

 the tentacles and are completely sessile. The mouth opens on the lower 

 surface of the head in front of the foot' (Annandale and Prashad, 1921, 

 p. 578). See Rao. 1923. p. 200, for a more extended account of external 

 characteristics. 



ANATOMICAL CHARACTERISTICS 



GENITALIA (plate 21, fig. 3). Male Organs. The seminal vesicle (SV) 

 is about 4 nun. long and nearly 1 nun. wide and is composed of small lobes 

 or tubercles surrounding the ovisperm duct. The si)erm duct (SPD) is a 

 small tube 7 mm. long, the portion near the ovisperm duct folded or coiled. 

 The prostate (PRS) is 3.5 mm. long and nearly 2 mm. wide, its low^r end 

 broadly rounded, its upper end narrowed to half the diameter of the lower 

 lobe. The prostate is composed of many long, branched diverticula, all of 

 wdiich radiate fan-wise from the common meeting place of the sperm duct 

 and vas deferens. In a cross section near the middle (fig. 8), there are 

 shown eight primary diverticula each of which is branched three or four 

 times toward the outer end, causing the outer surface of the prostate to 

 show twenty-four or more rounded projections. Each diverticulum is 

 branched as shown in fig. 9. The sperm duct and vas deferens meet on the 

 lower side of the prostate, the prostate diverticula radiating outward from 

 this junction. The ])rostate diA'erticula enter the sperm duct from which 

 the vas deferens proceeds as a small tube less than half the diameter of 

 the sperm duct. This condition is indicated in fig. 10. 



Both Rao and Larambergue describe the prostate as ellipitical in form, 

 but it was of the shape figured in all but one of the specimens examined 

 and the exception was regularly elliptical. There may, obviously, be some 

 variation in the shape of this organ. In its natural position, the prostate 

 lies against the uterus below the nidamental gland. The vas deferens is 

 a very long, narrow tube (about 12 mm. long). 



The penial complex (fig. 3) is made up of a short, cylindrical preputium 

 (3.5 mm. long) and a very long (17 mm.), narrow tube-like vergic sac 

 (VS) , which is five times the length of the preputium. In the figure of 

 Larambergue (1939, fig. 3, the vergic sac is shown four times the length of 

 the preputium. In Rao's figure (1923, p. 215), the vergic sac and the vas 

 deferens are confused and the enlarged vergic sac is entirely too short. The 

 figure by Larambergue (fig. 1) shows the vergic sac too short and the 

 preputium too long as compared with the specimens personally examined. 



There is a single retractor muscle (R^I) attached to the vergic sac near 

 the summit of the prejmtium. A heavy nerve (N) innervates this muscle. 

 Bands of supporting muscles (SM) are attached to the preputium on both 

 sides. In Rao's figure (1923, p. 215), the retractor muscle is shown as at- 

 tached to the vergic sac far above the preputium, which position was not 

 observed in any specimen examined. Larambcrgue's figure ( 1939, p. 288) 

 shows the muscle attached to the vergic sac just above the preputium, 

 which appears to be its natural position. 



Internally (plate 21, fig. 1), the preputium contains two long, vertical, 

 muscular pads or pilasters (]\IP) which extend the whole length of the 

 preputial cavity. There is a small muscular ring or diaphragm between the 

 vergic cavity and the preputial cavity. The verge (V) is a very long, nar- 



